Two previous calls from nationalist politicians for the document’s return fell on deaf ears.

MSPs Richard Lochhead and Jim Mather both called for its repatriation while they were in opposition.

“Keenly anticipated”

But now in power, the SNP administration is making inroads to see the 1305 document returned to Scotland.

Culture Minister Fiona Hyslop confirmed she had asked experts to report to her on the relic’s significance.

She said: “There has always been tremendous interest in this letter and repeated claims that it should rightfully reside in Scotland’s National Archives.

“I look forward to hearing the findings which will no doubt be keenly anticipated by those interested in this document, William Wallace and this important part of Scotland’s history.”

Wallace’s place in Scotland’s history was secured in 1297 after leading a Scottish army to victory against English forces at the Battle of Stirling Bridge.

He was arrested in Robroyston near Glasgow eight years later and taken into London where he was convicted of treason before being executed.

“Valuable and historic”

The medieval passport is said to have been found in a pouch on his belt before his death.

George MacKenzie, keeper of the records of Scotland, said he is keen to carry out research into the document.

He said: “It’s remarkable how a 700 year-old document still stirs such emotion today.

“I hope we can begin to solve the mystery.”

Oliver Morley, chief executive of the National Archives of Scotland said: “We welcome the opportunity for academic discussion on this subject and look forward to concluding on the purpose and origin of this valuable and historic document.”